This invention relates to a rotatable anchoring apparatus which supports a floating offshore structure rotatably in position in mooring the structure.
When a floating offshore structure such as a working boat or an oil rig is anchored at a predetermined location with an anchor cable, a rotatable anchoring apparatus is used to rotatably moor the floating offshore structure so as to leave it less at the mercy of wind and waves.
However, a conventional anchoring apparatus requires as many mobile windlasses as anchor cables, which is the cause of increased manufacturing costs. Furthermore, in a conventional windlass unit, an anchor cable is supported from below by a drum whose axis lies in a horizontal direction, so that a trouble is involved in loading and unloading the anchor cable for maintenance and inspection.